Fluid pressure brake



Aug. 25, 1936. I E. E. HEWITT 9 2,

' FLUID PRESSURE BRAKE Filed Oct. 13, 1931 ATTORNEY.

Patented Aug. 25, 1936 FLUID PRESSURE BRAKE Ellis E. Hewitt, Edgewood,Pa, assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., acorporation of Pennsylvania Application October 13, 1931, Serial No,568,545

7 Claims.

This invention relates to fluid pressure brakes, and moreparticularly toan automatic fluid pressure brake system in which the brakes are appliedby reducing the brake pipe pressure and released. when the brake pipepressure is increased.

It has heretofore been proposed, as disclosed in the pending applicationof Clyde C. Farmer, Serial No. 484,979, filed September 29, 1930, toprovide means for delaying or retarding the application of brakes oncars in the front portion of a train for a predetermined time, so as toobtain a more nearly synchronous application of the brakes in the frontand rear portions of a train, when the brake pipe pressure is reduced.This is particularly desirable in applying the brakes on a long train inorder to control-the gathering of the train slack so as to prevent aharsh running in of the slack with resultant excessive and damagingshocks.

Under certain conditions of operation, such as in a short train wherethe amount of slack is less than in a long train and the time requiredto effect an application of the brakes is also less, or in high speedservice, it is not considered necessary to delay the application ofbrakes in the front portion of the train. Under either of the conditionsjust mentioned, the brake pipe pressure employed is higher than employedin long trains and in low speed service, and this higher pressure isadapted to operate cut-out means for rendering the brake applicationdelay means inefiective.

In charging the brake pipe on a train, it is customary tofirst move theusual brake valve device to release position, in which fluid at highpressure is supplied directly from the usual main reservoir to the brakepipe and then after a predetermined time, the brake valve device ismoved to running position, in which the pressure of fluid supplied tothe brake pipe is governed by the adjustment of the usual feed valvedevice.

With the brake valve device in the release position, the brake pipe atthe front of the train becomes charged to substantially main reservoirpressure and, as a result, the brake equipments in the front of thetrain may become charged to a pressure sufficient to operate the cut-outmeans, above mentioned, to render the brake application delay meansineffective, when not desired.

The principal object of my invention is to provide means for obviatingthe above condition.

In carrying out my invention, I connect the emergency reservoir, thepressure in which controls the brake application delay cut-out means,

directly to the brake pipe through the triple valve device in the frontend. of the train, so that the emergency reservoir pressure is permittedto flow back to the brake pipe and equalize therewith When the brakevalve device is turned from release position to running. position, inwhich the brake pipe pressure is governed by the usual feed valvedevice.

Other objects and advantages will appear in the following more detaileddescription of my invention. a

In the accompanying drawing, the single figure is a diagrammatic view ofa brake controlling valve mechanism embodying my invention.

The brake controlling valve mechanism includes a triple valve devicecomprising a piston I having a piston chamber 2 at one side connected tothe usual brake pipe 3 and a valve chamber l at the opposite sideconnected to the mual auxiliary reservoir 5. The valve chamber 29 4contains a main slide valve 6 and an auxiliary slide valve 1 adapted tobe operated by piston I through the medium of a piston stem 8.

The triple valve device shown is of the retarded release type, having aretarded release stop member 9 engaging the inner end of the stem 8 andmain slide valve 6 and subject to the pressure of a spring Ill.

A selector valve device is provided comprising a pair of flexiblediaphragms II and I2 connected by a stem l3 and adapted to operate aslide valve [4 mounted in an intermediate valve chamber l5. A spring I 6acts on a member ll carrying a roller l8, so that said roller pressesthe valve M to its seat.

The selector valve device controls the cutting in and cutting out of abrake cylinder pressure inshot valve device comprising a ball valve i9and a piston 26) having a stem 2| adapted to engage the valve H). Aspring 22 acts on piston 20 and urges the same upwardly so as to unseatthe valve H).

A hold back valve device is provided comprising a flexible diaphragm 23subject to the pressure of a spring 24 and carrying a valve 25. Thechamber 26 at one side of the diaphragm 23 is open to the brake cylinderH, and the valve 25 controls communication from a passage 28, whichleads to the seat of slide valve 6, to chamber 26 and the brake cylinder21.

For controlling the operation of the selector valve device, a pilotvalve device is provided comprising a flexible diaphragm 29 having thechamber 30 at one side connected by a passage 50 to the'brake pipe 3,and having the valve chamber 32 at the opposite side connected, througha passage 33 with chamber 34 and the auxiliary reservoir 5. In chamber32 is mounted a slide valve 35 adapted to be operated by diaphragm 29,through a stem 36. A spring stop 31 engages the lower end of the stem 36and is subject tothe pressure of a spring 38, so that downward movementof stem 36 from the normal position shown in the drawing, is opposed bythe spring 38.

Cut-out means are provided for maintaining the selector valve device inthe position shown in the drawing for permitting a normal rate of buildup of brake cylinder pressure in effecting an application of the brakes.The cut out means comprises a flexible diaphragm 39 having at one side achamber 40 connected through passage M and passage and pipe 42 to theemergency'reservoir 43 and having at the other side a chamber 44 openthrough an aperture 45 in a partition wall to chamber 46 at one side ofthe selector valve diaphragm I I. A follower plate 41 is pressed intoengagement with diaphragm 39 by means of a spring 48 and is providedwith a pin IBI projecting into aperture 45.

In operation, when the brake pipe 3 is being initially charged withfluid under pressure, fluid under pressure flows from the brake pipethrough pipe and passage 49, passage 50, chamber 5| and ports 52 to thetriple Valve piston chamber 2.

In the front portion of the train, the rapid rate of increase in brakepipe pressure in piston chamber 2 moves the piston I and slide valves 6and I to retarded release position against the pressure of spring I 0,and in said position the piston I engages a stop rib 53. In the retardedrelease position, fluid under pressure flows from piston chamber 2through a feed groove 54 to valve chamber 4, and from thence throughport 55 in the retarded release stop member 9, chamber 34, and passageand pipe 56 to the auxiliary reservoir 5, thereby charging saidreservoir. Fluid under pressure is supplied directly from the brake pipepassage 50, past a check valve I to passage 42 leading to the emergencyreservoir 43, and also from passage 50 through passage 6| and cavity 60in the main slide valve 6 to passage 42. Cavity 60 is open through choke59, port 58 and port 51 to valve chamber 4, so that in initiallycharging the brake equipment, fluid under pressure will flow from thebrake pipe to valve chamber 4 through the last mentioned communication.When the auxiliary reservoir pressure in valve chamber 4 has been builtup to within a predetermined degree of the brake pipe pressure inchamber 2, the spring I0 shifts the piston I and slide valves 6 and I tothe full release position shown in the drawing, in which position thefull release charging port 62 is open, through which the final chargingof the auxiliary reservoir occurs.

In the rear portion of the train the rate of increase in brake pipepressure is insufiicient to move the piston I to retarded releaseposition against the opposing pressure of spring I0, so that piston Iand slide valves 6 and I move only to the full release position shown inthe drawing, in which position the auxiliary reservoir 5 is chargedthrough the full release charging port 62. The emergency reservoir ischarged past the check valve I05 and the pressure in the auxiliary andemergency reservoirs equalize through pipe and passage 42, ports 58 and51 in the main slide valve and valve chamber 4.

Diaphragm chamber 30 of the selector pilot valve device being connectedto the brake pipe 3 through passages 50 and. 49 is charged with flu atbrake pipe pressure, and chamber 32 at the opposite side of diaphragm 29is charged with fluid at auxiliary reservoir pressure through passage33.

The brake cylinder 21 is open to the atmosphere through pipe and passage63, chamber 26, passage 64, choke 65 and past the ball valve I9, throughpassage 28, cavity 65 in the main slide valve, passage 66 and exhaustchoke plug 61 when the triple valve device is in the full releaseposition shown in the drawing. When the triple valve device is in theretarded release position, passage 66 is lapped by the block (58 in themain slide valve, and the brake cylinder is then connected to theatmosphere through passage 69, retarded release choke I0, passage 66 andchoke plug 61.

In preparing a train for operation, it is customary to make a yard testof the braking apparatus prior to leaving a terminal. This test, inpart, comprises effecting an application and a release of the brakes andis necessary to properly position the selector valve slide valve I4 inaccordance with the position of the triple valve device in the train.

In releasing the brakes after an application, fluid at brake cylinderpressure supplied to cavity 65 in the main slide valve 6 flows throughDassage 69 to the seat of the selector pilot valve slide valve 35.

In the front portion of the train where the rate of increase in brakepipe pressure is rapid, the build up of brake pipe pressure in diaphragmchamber 36 of the pilot valve device deflects said diaphragm downwardlyagainst the opposing auxiliary reservoir pressure in valve chamber 32,and the pressure of spring 38. This deflection of diaphragm 29, which islimited by engagement of the spring stop 31 with the casing, shifts theslide valve 35 to a position in which passage II is connected through acavity I2 to an atmospheric passage I3, thereby venting diaphragmchamber 46 of the selector valve device. In this position of the pilotvalve slide valve 35, diaphragm chamber I4 of the selector valve deviceis connected through passage I5, port I6 and passage II in said slidevalve to passage 69 which is supplied with fluid under pressure from thebrake cylinder. Fluid at brake cylinder pressure thus supplied tochamber I4 of the selector valve device deflects the diaphragm I2 andmoves the slide valve I4 toward the left hand. This movement is limitedby engagement of diaphragm II with the casin and is suflicient toestablish communication from passage I8 to chamber I5 which is at alltimes 4' open to the atmosphere through an atmospheric passage I9.

When the brake cylinder pressure reduces by flow to the atmospherethrough the communication hereinbefore described, the stress of thedeflected diaphragms II and I2 return said diaphragms to their normalposition shown in the drawing. This return movement of the diaphragms IIand I2 to their unstressed position is relative to the slide valve I4,since a predetermined lost motion is provided between the slide valve I4and the slide valve operating stem I3 for this purpose. Thus, in thefront portion of the train the selector slide valve I4 will bepositioned so as to connect passage I8 to the atmosphere by way ofchamber I5.

When the auxiliary reservoir pressure in valve chamber 32 of the pilotvalve device is increased to a predetermined degree, spring 38 shiftsthe piston 36 and diaphragm 29 to the normal position shown in thedrawing, the movement being relative to the slide valve 35. i

In the rear portion of the train, the rate increase in brake pipepressure in diaphragm chamber .38 of the pilot valve deviceisinsufficient to overcome the increase in auxiliary reservoir pressure inchamber 32 and the pressure of spring 38. As a result, the slide valve35 remains in the position shown in the drawing in which positiondiaphragm chamber 14 of the selector valve device is connected to theatmosphere through passage 15, cavity 12 in the pilot slide valve 35and. atmospheric passage 13. Diaphragm chamber 46 of the selector valvedevice is supplied 'with fluid under pressure from the brake cylinderexhaust cavity 55 in the triple valve slide valve 6 by way of passage69, passage H in the pilot valve slide valve 85 and passage ll, so thatthe diaphragm H is deflected to position the slide valve l4 in theposition shown in the drawing. Then when the pressure in chamber 46 isreduced with the venting of the brake cylinder, the diaphragms H and I2move to their normal unstressed position shown in the drawing, thismovement being relative to slide Valve M for reasons hereinbeforeexplained.

Now, with the selector slide valve l4 properly positioned in the frontand rear portions of the train, if it is desired to effect anapplication of the brakes, fluid under pressure is gradually vented fromthe brake pipe 3 and triple Valve piston chamber 2 in the usual manner.

When a predetermined light reduction in pressure in piston chamber 2 isthus effected, auxiliary reservoir pressure in valve chamber 4 shifts.the piston l and auxiliary slide valve'l toward the right handrelativeto the main slide valve lished from the brake pipe 3 to a quickservice reservoir 82 by way of passage and pipe 88, passages 58 and BI,port 83 in the main slide valve 8, port 84, passage 85 and port 85 inthe auxiliary slide valve 1, port 8'! in the main slide'valve 6 andpassage and pipe 88.

The quick service reservoir having been connected to the atmosphere inrelease position of the main slide valve 6 through passage 88, choke 89,passage 88 and exhaust cavity 65,a rapid quick service reduction inbrake pipe pressure'is locally effected by the flow of fluid underpressure to said reservoir and this rapid reduction is adapted toserially transmit quick service action through a train of cars in orderto hasten the service application of brakes. Fluid under pressure thusvented to the quick service reservoir 82 tends to reduce by flow throughthe release choke 88 to the atmosphere, but said choke is of such sizethat no appreciable reduction thus occurs.

When the brake pipe pressure is reduced a predetermined amount greaterthan required to effect the quick service action just described, theauxiliary reservoir pressure in valve chamber 4 moves the piston l andslide valves 3 and l to service application position in which saidpiston engages a gasket 8|.

In service position of the slide valves and l, fluid under pressure ispermitted to flow from valve chamber 4 and the connected auxiliaryreservoir 5 to the brake cylinder 2'1 by way of port 92, passage 28,past the unseated ball valve [9, through passage B4, chamber 25, andthrough passage and pipe 63, so as to-efi'ect an application ofthebrakes;

a As hereinbefore described, the selector slide valve I 4, in the brakecontrolling valve devices in the front portion of the train, is in theleft hand position, so that chamber I88 at the lower side of the inshotvalve piston 28 is open to the atmosphere through passage 18, valvechamber l5 and atmospheric passage 19.

As a result, when the pressure of fluid supplied past the ball valve illto the brake cylinder and acting on the upper, inner seated area of saidvalve piston' becomes sufficient to overcome spring 22, said valvepiston is moved away from seat rib I8l, thereby exposing the full areaof said valve piston to fluid pressure which promptly moves the valvepiston to its lower position and permits ball valve I9 to seat, due togravity.

The inshot of fluid under pressure past the open valve 19 is adapted tomove the usual brake cylinder pistons (not shown) to applicationposition, then the ball valve seats. Further flow of fluid underpressure to the brake cylinder then occurs by flow of fluid underpressure from passage 28 through the choke plug 55 to passage 64.

is obtained by means of the initial inshot fol-' lowed by the restrictedbuild up just described, the brake cylinder pressure acting in chamber28 deflects diaphragm 23 downwardly against the opposing pressure ofspring 24. As the diaphragm 23'is thus moved downwardly, valve 25 isunseated and permits fluid under pressure to flow directly from passage28 to chamber 28 and from thence to the brake cylinder at an increasedrate for applying the brakes with the required force to obtain thedesired retardation.

In the rear portion of the train, the selector slide valve M ispositioned as shown in the drawing, as'hereinbefore explained, so as topermit fluid under pressure to flow from chamber E82 containing the ballvalve 18 through passage E83,

cavity 688 in the selector slide valve 58 and passage #8 to chamber 188at the lower side of the inshot valve piston 28. The fluid pressuresacting on the opposite sides 'of thevalve piston thus increase togetherwhich permits spring 22 to hold said valve piston in engagement withseat rib l8! and consequently hold the stem 2! in such a position as tomaintain the ball valve unseated to permit an unrestricted build up ofbrake cylinder pressure in the rear portion of the train.

In effecting an application of the brakes, the reduction in brake pipepressure in diaphragm chamber 38 of the pilot valve device permitsauxiliary reservoir pressure in valve chamber 32- pressure reduces byflow to the brake cylinder to a degree substantially equal to thereduced brake pipe pressure, the diaphragm 29 and stem 36 return totheir normal position shown in the drawing.

When the auxiliary reservoir pressure in the triple valve chamber 4 isreduced by flow to the brake cylinder to a degree slightly below thereduced brake pipe pressure in piston chamber 2, the piston I isoperated and moves the auxiliary slide valve I inwardly to service lapposition. This movement to service lap position occurs relative to themain slide valve 6 and is adapted to lap the service port 92 so as toprevent further flow of fluid under pressure to the brake cylinder.

If less than a full service reduction in brake pipe pressure isinitially eflected, then if desired a further application of the brakesmay be effected by making another reduction in brake pipe pressure.

Upon a further reduction in brake pipe pressure, the piston I andauxiliary slide valve 1 move relative to the main slide valve 6 toservice position in which the service port 92 is again uncovered topermit further flow of fluid under pressure from the auxiliary reservoirto the brake cylinder, thereby increasing the degree of brakeapplication.

In the traverse of the auxiliary slide valve 1 from service lap positionto service position, communication is established from the brake pipepassage 6| to the brake cylinder 21 through port 93 in the main slidevalve 6, port 94, passage 95 and port 95 in the auxiliary slide valve 1,port 96 in the main slide valve 6, passage 91, past check valve 98, andthrough passages 99 and 28. Fluid under pressure is thereby vented fromthe brake pipe to the brake cylinder to effect a local quick servicereduction in brake pipe pressure in order to hasten the operation of thebrake controlling valve devices on the train to effect a furtherapplication of the brakes.

To effect a release of the brakes after an ap plication, the brake pipepressure is increased in the usual manner.

The rapid rate of increase in brake pipe pressure in the front portionof the train moves the triple valve piston l and slide valves 6 and I toretarded release position in which fluid under pressure is supplied tovalve chamber 4 and the auxiliary reservoir 5 by flow from pistonchamber 2 through the feed groove 54 and at the same time by flow fromthe charged emergency reservoir 43 through pipe and passage 42, cavity60 in the main slide valve 6, choke 59, port 58 and port 5i. Theemergency reservoir 43 is also connected directly to the brake pipe 3through passage 42, cavity 60 in the main slide valve 6, passages GI and50 and passage and pipe 49, so that the pressures in the brake pipe andemergency reservoir equalizes and builds up to the high degree usuallyinitially obtained in the front portion of the train.

When the usual brake valve device (not shown) is turned from the releaseposition to the running position and the brake pipe pressure reduces tothat supplied by the usual feed valve device (not shown) fluid underpressure flows back from the emergency reservoir to the brake pipe andremains substantially equal to the brake pipe pressure.

When the pressure in valve chamber 4 is increased to within apredetermined degree of the pressure supplied by the feed valve deviceto piston chamber 2, spring I0 shifts the piston l and slide valves 6and I from retarded release position to full release position shown inthe drawing. This movement to full release position does not occur untilafter the emergency reservoir pressure is reduced to substantially brakepipe pressure,'and said movement closes the communication between saidreservoir and the brake pipe through cavity 60. However, the emergencyreservoir is connected in full release position of the triple valvedevice to valve chamber 4 and the auxiliary reservoir 2 as hereinbeforedescribed, and equalization of pressures in said reservoirs occurs.

In retarded release position of the triple valve device, fluid underpressure is vented from the brake cylinder to the atmosphere throughpipe and passage 63, chamber 26, passage 64, past the ball valve l9,through passage 28, cavity 65 in the slide valve 6, passage 69; choke10, passage 66 and choke plug 61 and fluid at brake cylinder pressureflows through passage 69 to the seat of the pilot valve slide valve 35.

The pilot valve device is operated by the rapid rate of increase inbrake pipe pressure at the head end of the train to supply fluid underpressure from passage 69 to diaphragm chamber 14 of the selector valvedevice, as hereinbefore described. However, since the selector slidevalve l 4 was initially properly positioned in the train, the deflectionof diaphragms l2 and II by fluid under pressure in chamber 14 does notmove the slide valve I4 from its left hand position. It will be obviousthat the pressure of fluid in diaphragm chamber 14 reduces with brakecylinder pressure and will be atmospheric pressure when the brakes arefully released.

Diaphragm chamber 40 of the hold back cutout means is in constantcommunication with the emergency reservoir 43 through passage 4| andpassage and pipe 42. The spring 48 acting on the cut-out diaphragm 39 isof such value that the normal emergency reservoir pressure carried inlong train operation will not deflect said diaphragm, but the highemergency reservoir pressure obtained in the diaphragm chamber 40 in thefront portion of the train in charging is suihcient to deflect saiddiaphragm and move stem I91 into engagement with the selector valvediaphragm I l Brake cylinder pressure acting at this time in theselector valve diaphragm chamber 14 plus the pressure of spring 48 morethan overbalances the high emergency reservoir pressure in chamber 40.The emergency reservoir pressure reduces when the brake pipe pressurereduces to that normally carried in the brake pipe, as hereinbeforedescribed, and spring 48 then deflects the diaphragm 41 back to itsnormal position. This occurs before the brake cylinder pressure inchamber 14 is 'materially reduced, so that the selector valve device atthe head end of the train is held in the proper or left hand position inspite of the fact that the emergency reservoir is initially charged to apressure higher than the normal brake pipe pressure employed in longtrain operation.

It will be noted from the above that if the high pressure initiallyobtained in the emergency reservoir were not permitted to reduce withthe reduction in brake pipe pressure when the triple valve device is inretarded release position, then such pressure acting on the cut-outdiaphragm 39 would deflect said diaphragm and move the selector slidevalve [4 to the position shown in the drawing, after the brake cylinderpressure in the selector valve diaphragm chamber 14 becomes reduced to apredetermined low degree.

With the slide valve M. in its right ha p s io an undesired rapid buildup of brake cylinder pressure would be obtained at the head end of thetrain in effecting an application of the brakes.

In the, rear portion of the train, the relatively slow rate of increasein brake pipe pressure moves he tr l v lv p o l an s de al 6 and t fuase. o ion sh wn n th d awin ln this. pos n. uid und P ssu is permittedto flow back from the emergency re r ir 43; hrou h pi e a passage 42 aports 58 and 51 in the mainslide valve 6 to valve ham e 4 and a e sam tm fluid un e r su e s pp ed from' he brak Dine th u h he ful el a e. hrs soer to va ve. c ame .15 and t ux li r e er r 5: Aft r e u lizationof emergency reservoir pressure and auxiliary reservoir pressure, theauxiliary reservoir charges up to brake pipe pressure with fluidsupplied through the charging port The mer n reservoir s ch d t ke pspressure by fluid. under pressure supplied past the check valve i635,and equalization of pressures. in both of said reservoirs occurs throughpassage 42 ports 58 and ,5: in the main slide valve 6 and valve chamber4.

In the full release position of the triple valve device fluid underpressure is vented from the brake cylinder'to efiect a release of thebrakes. The pilot valve device operates to supply fluid under pressurefrom the brake cylinder to the selector valve device, but the selectorslide valve 19 being initially properly set in the manner hereinbeforedescribed, its setting is not changed in effecting .a release of thebrakes,

In effecting ,aservice application of the brakes, if the brake pipepressure is reduced to a degree below the pressure obtained byequalization of the auxiliary reservoir into the brake cylinder, thenthe auxiliary reservoir pressure in chamber A maintains the piston i inservice position in engagement with gasket 9!. In releasing the brakesafter such an application, if the rate of increase in brake pipepressure is slow ,as in the rear portion of the train, the piston l isgradually moved from the service position toward release position and inso moving passes through the quick service position before the servicelap position is reached. 1

In the quick service position, fluid under pressure is upp f om th br kepine th u h passages 50 and 61, port 93 inthe rnain slide valve .6, port,94, passage 35 and port 95in the auxiliary slide valve; port 96 in themain slide valve and through passage 91 to the lower side of the valve98. The valve 98 is however pressed into engagement with its seat bymeans of a spring lot which is adapted to prevent flow of fluid frompassage 91 to passage 99 leading to the brake cylinder passage 28, whichat this time is open through the service port 92 to the valve chamber 4and auxiliary reservoir 5. By thus preventing flow of fluid underpressure from the brake pipe to valve chamber 4, it is possible toincrease the pressure in piston chamber 2 over the pressure-in valvechamber 4 so as to efiect movement of the triple valve parts to therelease position. If the spring we were not employed on check valve 99,it might, under certain conditions, be diflicult to obtain a release ofthe breaks.

The spring I96 acting on the check valve 98 is only of sufficient valueto ensure obtaining the required pressure differential on the triplevalve 7 piston l to move it to release position, and its pressure doesnot interfere with the quick service ac io o a whe he t ipl valve devi es m ved f m servi e la tqs iee s nhi spe s r e o o era in short trainswhere it is not considered necessary to retard the build up of brakecylinder pressure on cars at the head end of the train, the standardbrake pipe pressure employed is higher than employed in long trainoperation. The 'emergency reservoir 43, auxiliary reservoir 5 and other3311.. h sed men #1 15 ec m @b to the higher brake pipe pressure ininitially charging the train and effecting a release of the brakes afteran application, andthe high emergency reservoir pressure acting inchamber 40 is adaptedto'deflect the em; out diaphragm 39 toward theright hand to cutout position against the opposing pr sure of spring 58.The deflection of diaphrag moves pin I'U'l into engagement withdiaphragm]! and deflects said diae phragrn toward the right handsufficient for moving the slide valve [4 to'th'e" position shown in thedrawing in which position unretar'ded application of the brakesis'permitted to be effected in the manner hereinbefore described.

It will here be noted that the hold back out outmeans, just described,are not undesirably operated however, in operating a long trainemploying standard brake pipe pressure, even though the emergencyreservoir is overcharged to a higher pressure than normally carried inthe brake pipe, due to the fact that the initial high emergencyreservoir pressure obtained in charging the brake pipe is permitted toflew back to the brake pipe when the brake pipe pressure reduces to thatnormallycarrie d, as hereinbefore fully described.

The subject matter relating to the feature of venting,fiuid'underlpressurefrom a reservoir to the'brake pipe after anapplication of the brakes order to facilitate therelease of the brakesis claimed broadly in Clyde C. Farmers pending application Serial No.512,465, filed'May 20, 1932, which is in part a continuation of hisapplication, fiei ial 310.487, 988, filed October 11, 1930, and thesubject matter relating to the controlled build up ofbrake cylinderpressure in effecting an applica tion of the .brakes'is broadly claimedin the Earrner application serial No. 612,465.

While one illustrative embodiment of the invention has been described indetail, it is not my intention to limit its scope to that embodiment orotherwise than by theterms of .the appended claims. 7

-i-la ving. new described my invention, .what I claim as new and desiret o secure by Letters Patent, is:

1. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, an auxiliary reservoir, and an emergency reservoir, of atriple valve device operative upon a reduction in brake pipe pressure tosupply fluid under pressure from said auxiliary reservoir to said brakecylinder to efiect an application of the brakes, and operative upon arapid rate of increase in brake pipe pressure to vent fluid underpressure from said emergency reservoir to said brake pipe and at thesame time to supply fluid under pressure from said brake pipe to saidauxiliary reservoir, and operative upon a slower rate of increase inbrake pipe pressure to vent fluid under pressure from said emergencyreservoir to said auxiliary reservoir.

2. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, an auxiliary reservoir, and an emergency reservoir, of atriple valve device operative upon a reduction in brake pipe pressure tosupply fluid under pressure from said auxiliary reservoir to said brakecylinder to effect an application of the brakes, and operative upon arapid rate of increase in brake pipe pressure to vent fluid underpressure from said emergency reservoir to said brake pipe, and upon aslower rate of increase in brake pipe pressure to vent fluid underpressure from said emergency reservoir to said auxiliary reservoir, saidtriple valve device being operative irrespective of the rate of increasein brake pipe pressure to supply fluid under pressure from said brakepipe to said auxiliary reservoir.

3. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, an auxiliary reservoir, and an emergency reservoir, of atriple valve device operative upon a reduction in brake pipe pressure tosupply fluid under pressure from said auxiliary reservoir to said brakecylinder to effect an application of the brakes, and operative upon arapid rate of increase in brake pipe pressure to vent fluid underpressure from said emergency reservoir to said brake pipe at anunrestricted rate and to said auxiliary reservoir at a restricted rate,and operative upon a slower rate of increase in brake pipe pressure tovent fluid under pressure from said emergency reservoir only to saidauxiliary reservoir at a faster rate than when the rate of increase inbrake pipe pressure is rapid.

4. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, an auxiliary reservoir, an emergency reservoir havingcommunication with said brake pipe through which fluid under pressure issupplied from said brake pipe to said emergency reservoir, and a checkvalve interposed in said communication, of a triple valve deviceoperative upon a reduction in brake pipe pressure to supply fluid underpressure from said auxiliary reservoir to said brake cylinder to efiectan application of the brakes and operative upon a rapid rate of increasein brake pipe pressure to supply fluid under pressure from said brakepipe to said auxiliary reservoir and to open a by-pass around said checkvalve, and means for operating said triple valve device for closing saidby-pass upon substantial equalization of pressures in said auxiliaryreservoir and brake pipe.

5. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, an auxiliary reservoir, an emergency reservoir havingcommunication with said brake pipe through which fluid under pressure issupplied from said brake pipe to said emergency reservoir, and a checkvalve interposed in said communication, of a triple valve devicecomprising a casing having a passage connected to the brake pipe andoperative upon a reduction in brake pipe pressure to vent fluid underpressure from the brake pipe through said passage for effecting a quickservice reduction in brake pipe pressure and also operative upon areduction in brake pipe pressure to supply fluid under pressure fromsaid auxiliary reservoir to said brake cylinder for effecting anapplication of the brakes, said triple valve device being operative uponan increase in brake pipe pressure to vent fluid under pressure fromsaid emergency reservoir through said passage to the brake pipe and tovent fluid under pressure from the brake cylinder to effect a release ofthe brakes.

6. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, and an auxiliary reservoir, of a triple valve device movableupon a reduction in brake pipe pressure to a quick service position forventing fluid under pressure from said brake pipe to said brake cylinderand from said auxiliary reservoir to said brake cylinder, and movableupon a further reduction in brake pipe pressure to service position forclosing the communication from the brake pipe to the brake cylinder, andmeans operative in quick service position of said triple valve deviceupon an increase in brake pipe pressure and after equalization ofpressures in the auxiliary reservoir and brake cylinder for causing thebrake pipe pressure to increase a predetermined degree above auxiliaryreservoir pressure for moving the triple valve device to releaseposition.

'7. In a fluid pressure brake, the combination with a brake pipe, abrake cylinder, an auxiliary reservoir, and an emergency reservoir, of atriple valve device comprising a slide valve, and a piston operativeupon a reduction in brake pipe pressure to position said slide valve tosupply fluid under pressure from said auxiliary reservoir to said brakecylinder to effect an application of the brakes, and operative upon anincrease in brake pipe pressure to position said slide valve to ventfluid under pressure from said emergency reservoir to said brake pipe,said piston being operative at the same time as fluid under pressure isvented from the emergency reservoir to supply fluid under pressure fromsaid brake pipe to said auxiliary reservoir.

ELLIS E. HEWITT.

